This invention relates to a remote metering unit for an engine that is powered by liquid gasoline, liquid diesel, compressed propane, natural or other gas. This invention also relates to an engine allowing for the use of two or more fuels and/or fuels and oxidizers at the same time. Correct calibration of the remote metering unit will also allow the operation of a catalytic converter, an inexpensive hydrocarbon type, on a diesel engine.
Compressed propane, natural and other gases are efficient fuels for providing for higher efficiency in powering engines. Such compressed gaseous fuels typically provide higher power at relatively low cost in a more reasonably environmentally friendly manner than liquid fuels alone. Advantages include lower wear on the cylinders and rings, cleaner burning and extended oil changes due to less oil consumption together with the dryness of the gas (and due to the fact that there is no oil wash off or dilution in the engine).
Engine components for gas distribution, such as vaporizers/converters, fuel filters, fuel lock off are typically mounted adjacent to each other for use on existing engines. However, such components do not provide a total overall solution for the control of the combustion engines powered by such gaseous fuels; additional components are still required for these units. In addition, conventional supply of gaseous fuels to engines can result in higher emissions when the engine is warm as well as additional pressurized gas and hot water hose connections that can leak. In some instances a dual fuel operation is provided (propane for inside operation; liquid gasoline for outside operation). This necessitates two separate paths within/without a single unit. Emission control problems also remain substantially unsolved without the use of downstream treatment by multiple element catalytic converters and filters. A need still exists for a universal external, unitary fuel and/or oxidizer metering pod for internal combustion engines which can reduce the complexity of gas vaporization, and which can be retrofitted to existing liquid fueled engines. It would be desirable to provide for a precisely controlled metering pod for a compressed gaseous fuel and/or oxidizer utilized with an internal combustion engine to provide for the precise, consistent and repeatable controlled metering of the compressed gaseous fuel and/or oxidizer. The present invention meets these and other needs.
Briefly, and in general terms, the present invention provides for a fuel and/or oxidizer metering apparatus for internal combustion engines to provide for precise control of metering of a compressed gaseous fuel and for metering of multiple fuels, including gases and liquids. The apparatus of the invention dramatically reduces the number of components required for a compressed gas dual fueled engine suitable for combustion; reduces the cost of providing for a vaporized fuel/gas system interconnected to an internal combustion engine; and provides for an integrated control for engines powered by a compressed gas. The apparatus of the invention will simplify and reduce the cost of pollution control related to internal combustion engines. This includes meeting existing and proposed governmental emission limits with add-on downstream exhaust gas treatment such as by one or more catalytic converters or filters. The apparatus of the invention can also lower the cost of retrofitting internal combustion engines for operation on compressed gas or refitting existing compressed gas operating engines with a new low emissions compressed gas system; increase the maintenance interval and emission compliant operating interval of the metering system and its components; and provides for a dramatically simplified, reliably and precisely controlled remote metering system for internal combustion engines. The present invention further allows the operation of a common, hydrocarbon based, catalytic converter to be efficient on a diesel cycle engine.
The invention accordingly provides for a metering unit for a compressed combustible gas from a source of the compressed liquid combustible gas for service with a gas powered unit. The metering unit includes a pod with an inlet passage and an outlet passage, with a sealed passage in the pod connecting the inlet passage to the outlet passage. The pod may be remote from the gas powered unit, and a pipe may be provided connecting the outlet passage of the pod to the powered unit. Means are provided to connect the inlet passage to the source of compressed liquid combustible gas both internal to the tank or external to the tank, and means are provided to connect the outlet passage to the gas powered unit for providing gas thereto. An injector metering device is also disposed in the sealed passage that selectively meters compressed gas through the inlet passage to the outlet passage. In one embodiment, a pressure sensor is provided for sensing the pressure of the compressed gas in the inlet passage, and the metering of the injector may be controlled in response to the pressure sensor. In another embodiment, the outlet passage has an outlet passage axis, the injector metering device has a jet axis, and the jet axis is aligned with the outlet passage axis. In one aspect, the inlet passage has an inlet passage axis, and the inlet passage axis is substantially perpendicular to the jet axis.
In another aspect, the invention provides for temperature control means to control the temperature of the pod. The temperature control means may include an electric heater selectively operated to heat the gas in the outlet passage. The temperature control means may also be operative to control operation of the injector metering device. A thermal switch may also located in the pod to control the electric heater.
In another aspect, in which the powered unit has a controllable parameter, a temperature sensor is provided for sensing the temperature of the outlet passage, and means are provided to control the parameter of the metering unit in response to the temperature sensor. In another aspect, the controllable parameter may be the temperature of the metering unit injector, and the means to control the parameter may be a heater providing heat to the metering unit injector. The controllable parameter may be a temperature of the compressed gas, and the means to control the parameter may be an electric heater providing heat to the compressed gas.
In another aspect, the powered unit has an intake manifold and exhaust manifold, and a pipe is provided between the exhaust manifold and the intake manifold to provide for exhaust gas recirculation. An air mixing unit may be disposed between the pod and the intake manifold, and a unit temperature sensor may also be provided for sensing a measure reflective of the metering of the gas in the intake manifold, with means to control the exhaust gas recirculation in response to the unit temperature sensor.
A sensor may also be provided for measuring a parameter of the powered unit and generating a parameter output signal representing a measurement of the parameter. An electronic processing unit receives the output signal and controls the injector responsive to the parameter output signal. In one aspect, the powered unit includes an exhaust gas recirculation valve for controlling exhaust gas recirculation, and the sensor controls the exhaust gas recirculation valve. The powered unit may also have an adjustable mechanical manual control of the exhaust gas recirculation valve. In one aspect, the sensor is an oxygen sensor disposed in an exhaust of the powered unit. Means may also be provided for heating gas in the outlet passage, and the sealed passage, the injector and the means for heating may be integrated into the pod. A pressure regulator may also be connected to the sealed passage for regulating the pressure of the compressed gas.
A filter may be provided in the sealed passage of the pod between the inlet passage and the injector metering device, and means may be provided for cycling of the filter.